1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * Poly1305 authenticator algorithm, RFC7539
5 * Copyright (C) 2015 Martin Willi
7 * Based on public domain code by Andrew Moon and Daniel J. Bernstein.
10 #include <crypto/internal/poly1305.h>
11 #include <linux/kernel.h>
12 #include <linux/module.h>
13 #include <asm/unaligned.h>
15 static inline u64 mlt(u64 a, u64 b)
20 static inline u32 sr(u64 v, u_char n)
25 static inline u32 and(u32 v, u32 mask)
30 void poly1305_core_setkey(struct poly1305_key *key, const u8 *raw_key)
32 /* r &= 0xffffffc0ffffffc0ffffffc0fffffff */
33 key->r[0] = (get_unaligned_le32(raw_key + 0) >> 0) & 0x3ffffff;
34 key->r[1] = (get_unaligned_le32(raw_key + 3) >> 2) & 0x3ffff03;
35 key->r[2] = (get_unaligned_le32(raw_key + 6) >> 4) & 0x3ffc0ff;
36 key->r[3] = (get_unaligned_le32(raw_key + 9) >> 6) & 0x3f03fff;
37 key->r[4] = (get_unaligned_le32(raw_key + 12) >> 8) & 0x00fffff;
39 EXPORT_SYMBOL_GPL(poly1305_core_setkey);
41 void poly1305_core_blocks(struct poly1305_state *state,
42 const struct poly1305_key *key, const void *src,
43 unsigned int nblocks, u32 hibit)
45 u32 r0, r1, r2, r3, r4;
47 u32 h0, h1, h2, h3, h4;
48 u64 d0, d1, d2, d3, d4;
72 h0 += (get_unaligned_le32(src + 0) >> 0) & 0x3ffffff;
73 h1 += (get_unaligned_le32(src + 3) >> 2) & 0x3ffffff;
74 h2 += (get_unaligned_le32(src + 6) >> 4) & 0x3ffffff;
75 h3 += (get_unaligned_le32(src + 9) >> 6) & 0x3ffffff;
76 h4 += (get_unaligned_le32(src + 12) >> 8) | (hibit << 24);
79 d0 = mlt(h0, r0) + mlt(h1, s4) + mlt(h2, s3) +
80 mlt(h3, s2) + mlt(h4, s1);
81 d1 = mlt(h0, r1) + mlt(h1, r0) + mlt(h2, s4) +
82 mlt(h3, s3) + mlt(h4, s2);
83 d2 = mlt(h0, r2) + mlt(h1, r1) + mlt(h2, r0) +
84 mlt(h3, s4) + mlt(h4, s3);
85 d3 = mlt(h0, r3) + mlt(h1, r2) + mlt(h2, r1) +
86 mlt(h3, r0) + mlt(h4, s4);
87 d4 = mlt(h0, r4) + mlt(h1, r3) + mlt(h2, r2) +
88 mlt(h3, r1) + mlt(h4, r0);
90 /* (partial) h %= p */
91 d1 += sr(d0, 26); h0 = and(d0, 0x3ffffff);
92 d2 += sr(d1, 26); h1 = and(d1, 0x3ffffff);
93 d3 += sr(d2, 26); h2 = and(d2, 0x3ffffff);
94 d4 += sr(d3, 26); h3 = and(d3, 0x3ffffff);
95 h0 += sr(d4, 26) * 5; h4 = and(d4, 0x3ffffff);
96 h1 += h0 >> 26; h0 = h0 & 0x3ffffff;
98 src += POLY1305_BLOCK_SIZE;
107 EXPORT_SYMBOL_GPL(poly1305_core_blocks);
109 void poly1305_core_emit(const struct poly1305_state *state, void *dst)
111 u32 h0, h1, h2, h3, h4;
112 u32 g0, g1, g2, g3, g4;
122 h2 += (h1 >> 26); h1 = h1 & 0x3ffffff;
123 h3 += (h2 >> 26); h2 = h2 & 0x3ffffff;
124 h4 += (h3 >> 26); h3 = h3 & 0x3ffffff;
125 h0 += (h4 >> 26) * 5; h4 = h4 & 0x3ffffff;
126 h1 += (h0 >> 26); h0 = h0 & 0x3ffffff;
130 g1 = h1 + (g0 >> 26); g0 &= 0x3ffffff;
131 g2 = h2 + (g1 >> 26); g1 &= 0x3ffffff;
132 g3 = h3 + (g2 >> 26); g2 &= 0x3ffffff;
133 g4 = h4 + (g3 >> 26) - (1 << 26); g3 &= 0x3ffffff;
135 /* select h if h < p, or h + -p if h >= p */
136 mask = (g4 >> ((sizeof(u32) * 8) - 1)) - 1;
143 h0 = (h0 & mask) | g0;
144 h1 = (h1 & mask) | g1;
145 h2 = (h2 & mask) | g2;
146 h3 = (h3 & mask) | g3;
147 h4 = (h4 & mask) | g4;
149 /* h = h % (2^128) */
150 put_unaligned_le32((h0 >> 0) | (h1 << 26), dst + 0);
151 put_unaligned_le32((h1 >> 6) | (h2 << 20), dst + 4);
152 put_unaligned_le32((h2 >> 12) | (h3 << 14), dst + 8);
153 put_unaligned_le32((h3 >> 18) | (h4 << 8), dst + 12);
155 EXPORT_SYMBOL_GPL(poly1305_core_emit);
157 void poly1305_init_generic(struct poly1305_desc_ctx *desc, const u8 *key)
159 poly1305_core_setkey(desc->r, key);
160 desc->s[0] = get_unaligned_le32(key + 16);
161 desc->s[1] = get_unaligned_le32(key + 20);
162 desc->s[2] = get_unaligned_le32(key + 24);
163 desc->s[3] = get_unaligned_le32(key + 28);
164 poly1305_core_init(&desc->h);
169 EXPORT_SYMBOL_GPL(poly1305_init_generic);
171 void poly1305_update_generic(struct poly1305_desc_ctx *desc, const u8 *src,
176 if (unlikely(desc->buflen)) {
177 bytes = min(nbytes, POLY1305_BLOCK_SIZE - desc->buflen);
178 memcpy(desc->buf + desc->buflen, src, bytes);
181 desc->buflen += bytes;
183 if (desc->buflen == POLY1305_BLOCK_SIZE) {
184 poly1305_core_blocks(&desc->h, desc->r, desc->buf, 1, 1);
189 if (likely(nbytes >= POLY1305_BLOCK_SIZE)) {
190 poly1305_core_blocks(&desc->h, desc->r, src,
191 nbytes / POLY1305_BLOCK_SIZE, 1);
192 src += nbytes - (nbytes % POLY1305_BLOCK_SIZE);
193 nbytes %= POLY1305_BLOCK_SIZE;
196 if (unlikely(nbytes)) {
197 desc->buflen = nbytes;
198 memcpy(desc->buf, src, nbytes);
201 EXPORT_SYMBOL_GPL(poly1305_update_generic);
203 void poly1305_final_generic(struct poly1305_desc_ctx *desc, u8 *dst)
208 if (unlikely(desc->buflen)) {
209 desc->buf[desc->buflen++] = 1;
210 memset(desc->buf + desc->buflen, 0,
211 POLY1305_BLOCK_SIZE - desc->buflen);
212 poly1305_core_blocks(&desc->h, desc->r, desc->buf, 1, 0);
215 poly1305_core_emit(&desc->h, digest);
217 /* mac = (h + s) % (2^128) */
218 f = (f >> 32) + le32_to_cpu(digest[0]) + desc->s[0];
219 put_unaligned_le32(f, dst + 0);
220 f = (f >> 32) + le32_to_cpu(digest[1]) + desc->s[1];
221 put_unaligned_le32(f, dst + 4);
222 f = (f >> 32) + le32_to_cpu(digest[2]) + desc->s[2];
223 put_unaligned_le32(f, dst + 8);
224 f = (f >> 32) + le32_to_cpu(digest[3]) + desc->s[3];
225 put_unaligned_le32(f, dst + 12);
227 *desc = (struct poly1305_desc_ctx){};
229 EXPORT_SYMBOL_GPL(poly1305_final_generic);
231 MODULE_LICENSE("GPL");
232 MODULE_AUTHOR("Martin Willi <martin@strongswan.org>");